阔叶红松林凋落物-氮磷沉降耦合输入对土壤团聚体碳氮激发效应及稳定性影响

Comparative experimental plots will be established in the broad-leaved Korean pine forest and Korean pine plantation in Xiaoxing’an Mountains. Through the field control and lab simulation cultivation experiment of the litter removal, addition, retainment, simulated atmospheric N and P deposition, the characteristics of spatiotemporal variation in litter nutrient release, N and P mineralization of soil aggregate, C and N priming ratio, soil aggregate content of water stability and fractal dimension will be studied. The influence of synergistic impact of litter, N and P depositions on C and N priming effect of soil aggregate and their stability will be revealed. Quantitative relationship models among litter nutrient release, C and N priming effect of soil aggregate, and soil aggregate stability will be built under the condition of the litter removal, addition, retainment, simulated atmospheric N and P deposition. The influential mechanism of litter and simulated N and P depositions coupling function on C and N priming effect and the stability of soil aggregate will be interpreted. Whether the litter removal, addition, retainment, simulated N and P depositions, and their interactions have coupling effect on C and N mineralization of soil aggregate or not will be explored. If this coupling effect exists, is it positive or negative? How will this coupling effect influence soil aggregate stability？This study will provide the basic data and science and technology support for the increased soil quality of broad-leaved Korean pine forest and pine plantations.

以小兴安岭阔叶红松（Pinus Koreiensis）林和红松人工林(对照)作为对比试验样地，通过去除、添加、保留凋落物和模拟大气氮磷沉降野外控制和室内模拟培养实验，研究凋落物养分释放、土壤团聚体碳氮矿化，CN激发比率及土壤水稳性团聚体含量和分形维数时空变化特征，揭示凋落物及其NP沉降协同作用对土壤团聚体碳氮激发效应及其稳定性的影响。构建去除、添加、保留凋落物和模拟氮磷沉降下凋落物养分释放与土壤团聚体碳氮激发效应和土壤团聚体稳定性之间的定量关系模型，阐释凋落物和模拟氮磷沉降耦合作用对土壤团聚体碳氮激发效应及其稳定性的影响机制。探讨去除、添加、保留凋落物和模拟NP沉降及其交互作用是否对土壤团聚体碳氮矿化有激发效应。如果这种激发效应存在的话，它是正效应还是负效应？它对土壤团聚体稳定性产生怎样的影响？此项研究将为阔叶红松林和红松人工林土壤质量的提高提供基础数据和科技支撑。

大气氮磷沉降和凋落物添加耦合输入，促使森林凋落物分解和养分释放，而这种输入的增加能影响土壤团聚体中原来固持有机碳氮的释放，形成“激发效应”，但迄今其变化规律与机制尚不清楚。此项研究以小兴安岭阔叶红松林和红松人工林(对照)作为对比试验样地，通过去除、添加、保留凋落物和模拟大气氮磷沉降野外控制和室内模拟培养实验，以及野外土壤和凋落物样品采集、室内培养、样品分析和数据统计等相结合的方法，探讨了以下问题：①大气降雨中有机碳含量及输入量；②新鲜凋落物碳水化合物含量变化特征；③模拟氮磷沉降与凋落物添加对凋落物LFH层碳水化合物分解与释放影响；④氮磷沉降与凋落物添加对凋落物LFH层NP分解与释放影响；⑤影响凋落物养分释放因素的分析；⑥凋落物碳氮磷年固定量与储量研究；⑦水稳性团聚体与非水稳性团聚体组成特征及稳定性；⑧土壤水稳性与非水稳性团聚体养分的分布特征；⑨氮磷沉降与凋落物添加对土壤物理性质的影响；⑩氮磷沉降及凋落物添加对土壤活性有机碳库及氮磷的影响；⑪外源有机物与温度耦合作用对红松阔叶混交林土壤有机碳的激发效应；⑫氮磷沉降和凋落物添加对土壤团聚体有机碳库的影响；⑬氮磷沉降与凋落物添加对土壤C、N、P循环酶活性的影响；⑭氮磷沉降对土壤团聚体微生物群落组成的影响；⑮氮磷沉降下土壤团聚体活性碳氮与细菌和真菌群落组成的关系；⑯室内培养凋落物添加-模拟氮磷沉降耦合输入对土壤水稳性团聚体碳激发效应及稳定性的影响；⑰室内培养凋落物添加-模拟氮磷沉降耦合输入对土壤水稳性团聚体氮激发效应及稳定性的影响。本项研究旨在阐明凋落物养分释放、土壤与土壤团聚体碳氮含量，及土壤水稳性团聚体和非水稳性团聚体组成时空变化特征，揭示凋落物及其NP沉降协同作用对土壤团聚体碳氮激发效应及其稳定性的影响。阐释凋落物和模拟氮磷沉降耦合作用对土壤团聚体碳氮激发效应及其稳定性影响机制，为阔叶红松林和红松人工林土壤质量的提高提供基础数据和科技支撑。